Australia's prime minister said everything that possibly could be done to find the plane would be done, but cautioned, "We cannot be certain of success."
Najib's wife, Rosmah Mansor, also traveled to Perth, where she met with Danica Weeks, whose husband, Paul Weeks, was among those on Flight 370. Weeks said the meeting gave her some comfort and confidence the Malaysians are committed to finding answers. But she also said the pervasive uncertainty surrounding the plane's fate had made coping with the loss impossible.
"You cannot grieve for someone unless you have something concrete," Weeks told Australia's Channel 9.
Two British vessels — a nuclear-powered submarine with advanced underwater search capability and the British Survey ship HMS Echo — have joined the hunt, Houston said. The Ocean Shield, an Australian warship carrying a U.S. device that detects "pings" from the plane's flight recorders, was en route.